If they carry out this lower-level job as best they can, then either they get promoted very quickly or they stay doing the job properly and feeling self-esteem that they're taking it seriously and that's valued and appreciated. Then they get to go home and get on with the rest of their lives.
If someone accepts the level of the job they're doing, and does it appropriately, everyone's happy. If they resent it, it doesn't benefit anyone.
.
A bit off subject but you struck upon a truth that I have seen in coworkers and family members, basically everywhere I look. You will be happier and more successful if you accept that when you cross the sidewalk and enter the job site it doesn't matter if you are the CEO of General motors or the guy that mows the lawn in front of the CEO's office, you are there because you can make a buck for the owners or shareholders or whoever signs the paycheck. Maybe the lawn has to be mowed because someone with an architecture degree decided that the green space was a necessary addition to create the impression for potential business investors or partners that this building is occupied by a business that has a concern and connection to the environment and the attention to detail to keep the lawn nicely mowed. Who cares why?- You are being paid to mow the lawn by someone that thinks it is worth it to pay you to mow the lawn so be a lawn mower and get paid.
In college I worked a graveyard job pumping gas. Even near a major freeway it was a long boring night and some guys would do anything but stay busy washing windows or stocking product or sweeping the lot. They generally lasted a few months and got caught sleeping or worse and disappeared. I kept busy and started trying to sell extra services and I soon had a regular customer base of maybe 20 customers that would come in at 2 in the AM for oil changes and such because I was seldom too busy and always glad to see them. I didn't get any more pay for the 'extra' work I did, but I kept the job as long as I needed to and never had a night of sitting and hating my position.
Maybe that is a side benifit of PTSD, I like to stay busy so I don't have time to sit and think about the things i don't want to think about, and thats exactly what every boss that has ever hired me wanted from me, a universal truth for any boss for anyone.
When you take a job, take it to do it. If you resign yourself to a job you know is below your skills and pay level you have to get through it so do your best and get through it- all the time looking for an opportunity for that higher level work.
One more side note- When you are working below your skill level you will often find other people in similar situations and those of you that are working through it will recognize each other and you will recognize the slackers among you that are just punching the clock and trying to stay awake till the bell rings. When one of you finds the opportunity you are all looking for (hopefully it's you) there are often other opportunities in the same business and it is a positive to be networked with the other hardworking people you have met in the low paying "make do" job. No one is going to find the better job and then call the slackers they met at their old "make do" job and tell them about the great new opening they should apply for. That's not gonna happen.
Sorry about the side tracking of the thread, but I saw an opportunity to help- hope this does.